I've just bought a NanoPi M4 (the 2GB version), with the SATA hat and the 12V/2A PSU.

My intention is to have two 3.5" 5400rpm WD NAS HDDs connected, but I am not sure if the 12V/2A PSU will be enough to power both the HDDs and the M4 board. The description page of the SATA hat says that:

A 12V/2A power can drive one 3.5" hard disk or four 2.5" hard disks. To drive four 3.5" hard disks a 12V/5A power is needed

But it doesn't say anything about my case (two 3.5" HDDs).

Has anyone tried this or do you guys know if the 12V/2A would be enough?

Check a spec of your HDD - for 3.5" it's should be something like: "+12V/0.5A +5V/0.7A" and try to make a calculation with respect to conversion efficiency around 0.75.

For this particular case (it's a spec from old SP1614C Samsung 3.5" HDD - so we will have 12V/1.78A for 2HDD) looks like 12V/2A is OK for 2 HDDs, but for your WD HDD it can be different.

PS: you need to be sure, that you power supply really provide 2A on 12V, which may not happens with no-name devices.

PPS: just found 2.5" IDE HDD with +5V/1A (Toshiba MK1234GAX) (+ IDE to SATA adapter board) - 4 such drivers will consume more energy at peak than 2x3.5" Samsung HDD from above - but Hat Spec says that they should work (while I believe that they wouldn't). So you need to test you configuration - it's looks like only a option.

ayaromenok wrote:PS: you need to be sure, that you power supply really provide 2A on 12V, which may not happens with no-name devices.

Very much the case. I got 2 power supplies from a local supplier, non branded Chinese models. Both were claimed to be 5V 4A and 5V 5A but ended up being useful only at 5V 1A before they dipped. I ended up getting some Meanwell supplies from Mouser that have a far more stable output.

The choice from FA to design now with onboard regulation and using 12V input is a good one as this removes the issues were a lot of users have failures due to the 5V supplies being insufficient to power the devices. You see that a lot with Raspberry Pi.